Hydrogen fluoride production tail gas recovery device

Abstract

The utility model relates to fluorine chemical industry environmental protection equipment technical field, concretely is a kind of hydrogen fluoride production tail gas recovery device, including condensing box, absorption tank and purification tank, the first condenser, secondary condenser and separate end plate are equipped in condensing box, realize gradient condensation, bottom liquid-collecting tank is automatically discharged by discharge pipe with electric valve, liquid level sensor real-time monitoring;Side is equipped with clean mouth and is equipped with transparent observation window, it is convenient to wash and maintain.Separately through dilute sulfuric acid spray head and ammonia water spray head vertical shower, high -efficient absorption residual HF, molecular sieve adsorption layer and baffle demisting layer are equipped in purification tank, realize depth drying and demisting, fluorine plastic corrugated packing layer, activated carbon layer and molecular sieve adsorption layer are integrated in slidable net rack, cooperate through bearing rod and filling mouth both sides sliding groove, realize modularization pull replacement.The device recovery efficiency is high, operation is stable, maintenance is convenient, it is applicable to fluorine chemical industry field tail gas treatment.

Description

Technical Field

[0001] This utility model relates to the field of environmental protection equipment technology in fluorochemical industry, specifically a hydrogen fluoride production tail gas recovery device. Background Technology

[0002] Currently, commonly used industrial waste gas recovery methods mainly include water absorption, alkaline absorption, and condensation. Condensation, through low-temperature cooling, condenses gaseous HF into liquid hydrofluoric acid, achieving resource recovery. However, condensation alone is insufficient to reduce the HF concentration in waste gas below emission standards, especially under high humidity or fluctuating conditions, where incomplete condensation, frosting, and blockage are common problems. While absorption can further reduce HF concentration, traditional packed towers often use a single absorption medium, resulting in low absorption efficiency, difficulty in handling byproducts, and easy blockage of the packing material. Although some systems incorporate activated carbon or molecular sieve adsorption, replacing the adsorption material is difficult, maintenance costs are high, and the system lacks automated monitoring, leading to poor operational stability.

[0003] Furthermore, existing equipment generally suffers from low structural integration and fragmented functional modules. The condenser and absorption tower are set up independently, resulting in a complex system and large footprint; untimely condensate collection can easily lead to overflow accidents; and the packing layer is mostly fixed, requiring disassembly for replacement, which is time-consuming and labor-intensive, further reducing operational reliability. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this utility model provides a hydrogen fluoride production tail gas recovery device.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, this utility model provides the following technical solution: A hydrogen fluoride production tail gas recovery device of this utility model includes a condensation box, an absorption box, and a purification box. The condensation box is equipped with a staged condensation module, which includes a primary condenser and a secondary condenser. A liquid collection tank is provided at the bottom of the condensation box. An end plate is provided between the primary and secondary condensers, and an opening is provided on the end plate. One end of the condensation box is provided with an air inlet, and the other end is connected to the absorption box through a pipe. The absorption box is connected to the purification box through a pipe. An absorption module is provided in the absorption box, and a purification module is provided in the purification box. An air outlet is provided at the top of the purification box. The absorption module includes a fluoroplastic corrugated packing layer and an activated carbon layer. The absorption box is provided with a dilute sulfuric acid inlet and an ammonia water inlet. The dilute sulfuric acid inlet is adapted to the fluoroplastic corrugated packing layer, and the ammonia water inlet is adapted to the activated carbon layer. The purification module includes a molecular sieve adsorption layer and a baffle plate demister layer. The molecular sieve adsorption layer is located below the baffle plate demister layer.

[0008] Preferably, the absorption box includes a primary absorption layer and a secondary absorption layer, the primary absorption layer and the secondary absorption layer are connected, the fluoroplastic corrugated packing layer is disposed in the primary absorption layer, the activated carbon layer is disposed in the secondary absorption layer, a dilute sulfuric acid nozzle is provided on the dilute sulfuric acid inlet, an ammonia nozzle is provided on the ammonia inlet, the dilute sulfuric acid nozzle is perpendicular to the fluoroplastic corrugated packing layer, and the ammonia nozzle is perpendicular to the activated carbon layer.

[0009] More preferably, the side of the condenser box is provided with at least two cleaning ports, and the cleaning ports are adapted to the primary condenser and the secondary condenser. A sealing cover is installed on the cleaning port by means of a bolt structure, and the sealing cover is provided with a transparent observation window.

[0010] Preferably, the device also includes a mesh frame, wherein the fluoroplastic corrugated packing layer, the activated carbon layer and the molecular sieve adsorption layer are disposed within the mesh frame, and the absorption box and the purification box are provided with filling ports, and the mesh frame is slidably installed on the filling ports.

[0011] Preferably, a support frame is provided below the demisting layer of the baffle plate, and protective covers are provided on the sides of the support frame and the mesh frame. The support frame and the protective covers are slidably installed on the filling port.

[0012] More preferably, the filling port is provided with bearing grooves on both sides, and the bearing frame and the protective cover on the side of the mesh frame are slidably connected to the bearing grooves through bearing rods.

[0013] Preferably, at least two drain pipes are provided below the condenser and the absorption tank, and the drain pipes are respectively connected to the liquid collection tanks below the primary condenser, the secondary condenser, the fluoroplastic corrugated packing layer and the activated carbon layer. The drain pipes are equipped with drain valves, and the condenser is equipped with a liquid level sensor located above the drain pipe. The drain pipe of the absorption tank is equipped with a flow controller.

[0014] (III) Beneficial Effects

[0015] Compared with the prior art, this utility model provides a hydrogen fluoride production tail gas recovery device, which has the following beneficial effects:

[0016] This technical solution employs a staged cooling design with primary and secondary condensers, combined with end plates to guide airflow, achieving efficient gradient condensation and significantly improving the recovery rate of liquid hydrofluoric acid. The bottom collection tank and independent drain pipe, combined with a liquid level sensor, automatically control the opening and closing of the corresponding drain valve, enabling intelligent draining. The side cleaning port is equipped with a transparent observation window and sealing cover, facilitating online inspection and maintenance and improving operational stability.

[0017] The absorption tank is equipped with a primary absorption layer and a secondary absorption layer, which are precisely sprayed through dilute sulfuric acid nozzles and ammonia nozzles, respectively, to achieve efficient chemical absorption and neutralization of HF, generating recyclable byproducts such as ammonium fluorosilicate, resulting in high resource utilization. The drain pipe is equipped with a flow controller to monitor the consumption of absorbent and the reaction process, optimizing operating parameters.

[0018] The purification chamber is equipped with a molecular sieve adsorption layer and a baffle plate demister layer to deeply remove residual moisture, trace impurities and acid mist, ensuring that the outlet gas is clean and dry and meets ultra-low emission standards.

[0019] All functional layers are integrated into a sliding space frame structure, and modular pull-out replacement is achieved through the cooperation of support rods and sliding grooves, making maintenance convenient, safe, and efficient. The overall device has a compact structure, a high degree of automation, and strong corrosion resistance, making it suitable for continuous industrial production, effectively reducing operating costs, and possessing good potential for widespread application. Attached Figure Description

[0020] Figure 1 This is a front view schematic diagram of the overall device of this utility model;

[0021] Figure 2 This is a rear view schematic diagram of the overall device of this utility model;

[0022] Figure 3 This is a schematic cross-sectional view of the overall device of this utility model;

[0023] In the diagram: 1. Condensation chamber; 2. Absorption chamber; 3. Purification chamber; 4. Air inlet; 5. Primary condenser; 6. Secondary condenser; 7. Partition plate; 8. Primary absorption layer; 9. Secondary absorption layer; 10. Dilute sulfuric acid inlet; 11. Ammonia inlet; 12. Dilute sulfuric acid nozzle; 13. Ammonia nozzle; 14. Fluoroplastic corrugated packing layer; 15. Activated carbon layer; 16. Molecular sieve adsorption layer; 17. Baffle plate demister layer; 18. Support frame; 19. Air outlet; 20. Protective cover; 21. Mesh frame; 22. Support rod; 23. Drain pipe; 24. Drain valve; 25. Flow controller; 26. Liquid level sensor; 27. Sealing cover; 28. Transparent observation window. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Please see Figure 1-3This utility model discloses a hydrogen fluoride production tail gas recovery device, comprising a condensation box 1, an absorption box 2, and a purification box 3. The condensation box 1 is equipped with a staged condensation module, which includes a primary condenser 5 and a secondary condenser 6. A liquid collection tank is located at the bottom of the condensation box 1. A partition plate with an opening is provided between the primary condenser 5 and the secondary condenser 6. One end of the condensation box 1 has an air inlet 4, and the other end is connected to the absorption box 2 via a pipe. The absorption box 2 is connected to the purification box 3 via a pipe. The chamber 2 is equipped with an absorption module, and the purification chamber 3 is equipped with a purification module. The top of the purification chamber 3 is equipped with an air outlet 19. The absorption module includes a fluoroplastic corrugated packing layer 14 and an activated carbon layer. The absorption chamber 2 is equipped with a dilute sulfuric acid inlet 10 and an ammonia water inlet 11. The dilute sulfuric acid inlet 10 is adapted to the fluoroplastic corrugated packing layer 14, and the ammonia water inlet 11 is adapted to the activated carbon layer 15. The purification module includes a molecular sieve adsorption layer 16 and a baffle plate demister layer 17. The molecular sieve adsorption layer 16 is located below the baffle plate demister layer 17.

[0026] In this technical solution, the condenser 1 uses a gradient condensation process between a primary condenser 5 (e.g., -10 to -5℃) and a secondary condenser 6 (e.g., -25 to -20℃) to condense 60-65% of the hydrogen fluoride (HF) and fluorosilicic acid (H2SiF6) in the exhaust gas into a liquid state, achieving gas-liquid separation and preliminary capture. After condensation, the exhaust gas, containing 35-40% residual fluorides, enters the absorption tank 2. The primary absorption layer 8, through dilute sulfuric acid spraying and fluoroplastic corrugated packing, converts silicon fluoride (SiF4) into recyclable fluorosilicic acid. The secondary absorption layer 9, through ammonia spraying and activated carbon layer 15, neutralizes the residual HF to generate ammonium fluoride (NH4F). This dual-stage absorption increases the fluoride removal rate to 99%. Finally, the exhaust gas enters the purification tank 3, where the molecular sieve adsorption layer 16 removes trace amounts of fluorides, and the baffle plate demister layer 17 separates droplets, ensuring that the exhaust gas emission concentration is ≤1 mg / m³. 3 The optimized technologies, such as the drain pipe 23 and the sliding mesh frame 21, further improve operation and maintenance efficiency and equipment adaptability, solving the pain points of low absorption efficiency, cumbersome operation and maintenance, and severe corrosion of traditional devices.

[0027] Condenser 1 is the core of exhaust gas pretreatment. It achieves efficient collection and convenient operation and maintenance through gradient condensation structure optimization. The specific principle is as follows:

[0028] The exhaust gas enters through inlet 4 of condenser 1 and first flows through primary condenser 5. 80-85% of the H2SiF6 in the exhaust gas liquefies at low temperature, dripping down the Hastelloy heat exchange tube wall into the lower collection tank. The remaining exhaust gas is guided into secondary condenser 6 through the end plate opening, where 30-35% of the HF further liquefies and flows into the corresponding collection tank. The two-stage condensation utilizes a temperature gradient to capture high-boiling-point components first and low-boiling-point components later, avoiding insufficient capture efficiency caused by a single condensation temperature.

[0029] Two drain pipes 23 below the condenser 1 correspond to the collection tanks of the first-stage and second-stage condensers 6, respectively. Two level sensors 26 can be installed above the drain pipes 23, one corresponding to 70% of the collection tank capacity and the other to 30% of the collection tank capacity, to monitor the liquid product level in real time: when the liquid level reaches 70% of the collection tank capacity, the corresponding drain valve 24 is opened to transport the first-stage H2SiF4 solution and the second-stage HF solution to a dedicated temporary storage tank to avoid mixing and affecting subsequent purification; when the liquid level drops to the 30% low liquid level threshold, the valve is closed to prevent empty draining or overflow of accumulated liquid, thus achieving separate collection and precise control.

[0030] The cleaning port, which is compatible with the first and second stage condensers 6, is sealed with a cover 27 by bolts. The transparent observation window 28, such as fluorine-resistant quartz glass, allows for real-time observation of the scaling on the heat exchange tubes. When the scaling thickness on the tube wall is ≥2mm and affects the heat exchange efficiency, the cover 27 is removed and a high-pressure water gun or 5% dilute hydrochloric acid is introduced through the cleaning port to remove the scale layer.

[0031] Absorption tank 2 adopts a stratified design with primary acid absorption and secondary alkali absorption. It achieves deep defluorination through spraying and the synergistic effect of packing / activated carbon. The specific principle is as follows:

[0032] Fluoroplastic corrugated filler layer 14 is filled in the mesh frame 21, and the mesh frame 21 is slidably installed in the filling port of the first-stage absorption layer 8 of the absorption box 2 through the bearing slide groove; when in use, the dilute sulfuric acid inlet 10 can be connected to the dilute sulfuric acid pump and dilute sulfuric acid storage tank through the pipeline to introduce dilute sulfuric acid, and the dilute sulfuric acid nozzle 12 sprays 10-15% dilute sulfuric acid to form 50-100μm droplets, which come into contact with the countercurrent.

[0033] In the exhaust gas, SiF4 reacts with dilute sulfuric acid solution to generate H2SiF6. The corrugated structure of the fluoroplastic filler increases the gas-liquid contact time, ensuring a complete reaction.

[0034] The activated carbon layer 15 is filled in the mesh frame 21 and installed in the secondary absorption layer 9 of the absorption box 2. When in use, the ammonia water inlet 11 can be connected to an external ammonia water pump and ammonia water storage tank through a pipeline to introduce ammonia water, and 20-25% ammonia water is sprayed by the ammonia water nozzle 13, with the droplets evenly covering the surface of the activated carbon.

[0035] Residual HF reacts with ammonia to generate NH4F, catalyzing the reaction and achieving an HF removal rate of over 95%. Simultaneously, activated carbon adsorbs unreacted trace amounts of SiF4, preventing it from entering subsequent purification modules.

[0036] Purification chamber 3 achieves ultra-low emissions of exhaust gas through molecular sieve adsorption and baffle plate demisting. The specific principle is as follows:

[0037] The 13X type fluoride ion selective molecular sieve is filled in the mesh frame 21 and slidably installed at the bottom of the purification box 3 via a support groove: the residual 5-10 mg / m³ in the exhaust gas3 Fluorides are adsorbed through ion exchange.

[0038] The baffle plate demister layer 17 is installed on the support frame 18, and the support frame 18 is slidably connected to the filling port slide of the purification box 3 through the protective cover 20. When the exhaust gas passes through the baffle plate, due to the sudden change in airflow direction, the mist droplets are impacted by inertia and fall along the plate wall to the collection tank below. The protective cover 20 is covered with fluororubber material to ensure the sealing of the protective cover 20 at the filling port and avoid leakage. At the same time, the protective cover 20 is connected to the absorption box 2 and the purification box 3 through the sealing bolt structure.

[0039] When the fluoroplastic corrugated packing layer 14, activated carbon layer 15, molecular sieve adsorption layer 16, and baffle plate demister layer 17 need to be replaced, loosen the filling port sealing bolts, pull them out along the slide groove through the bearing rod 22, and directly replace the internal packing, which greatly improves the operation and maintenance efficiency.

[0040] The liquid level sensor 26, drain valve 24, flow controller 25, primary condenser 5, and secondary condenser 6 in this technical solution can be controlled by a conventional PLC controller, and the liquid level sensor 26, drain valve 24, flow controller 25, primary condenser 5, and secondary condenser 6 can be connected to AC mains power through a conventional circuit.

[0041] Detailed Workflow

[0042] Stage 1: Staged condensation and collection

[0043] The tail gas from hydrogen fluoride production is piped into the inlet 4 of condenser 1, and first flows through the first-stage condenser 5: 80% H2SiF6 is liquefied, and drips down the pipe wall to the collection tank, reducing the HF concentration in the tail gas to 8%.

[0044] The exhaust gas enters the secondary condenser through the opening of the partition plate. The HF concentration of 6:30% is liquefied and drips into the corresponding collection tank. The HF concentration in the exhaust gas drops to 5.6%. It then enters the absorption tank 2 through the pipeline from the outlet of the condenser 1.

[0045] When the liquid level in the primary condenser's collection tank 5 reaches 70%, the level sensor 26 triggers the PLC controller to open the corresponding drain pipe 23 and drain valve 24, transferring 25% concentration H2SiF6 to the fluorosilicic acid storage tank; when the liquid level drops to 30%, the valve closes, with a single drain volume of approximately 0.5 m³. 3 ;

[0046] When the liquid level in the secondary condenser's 6th collection tank reaches 70%, the corresponding valve is opened to transfer 30% HF to the hydrogen fluoride storage tank, thus achieving separate collection of the two products and avoiding mixing that could affect the purification purity.

[0047] Phase 2: Dual-stage absorption and defluorination in absorption box 2

[0048] After condensation, the exhaust gas enters the primary absorption layer 8 from the bottom of the absorption box 2 and flows through the fluoroplastic corrugated packing layer 14. The top dilute sulfuric acid nozzle 12 sprays 12% dilute sulfuric acid, and the droplets come into countercurrent contact with the exhaust gas, and SiF4 reacts to generate H2SiF6.

[0049] Open the drain valve of the drain pipe 23 at the bottom of the primary absorption layer 8 to transport the solution to the fluorosilicic acid purification unit. The single drain volume is approximately 1m³. 3 The flow controller 25 detects that its drain valve and flow controller 25 can be controlled by a PLC controller.

[0050] After primary absorption, the tail gas flows to secondary absorption layer 9 and through activated carbon layer 15. 22% ammonia water is sprayed from the top ammonia water nozzle 13. HF reacts with ammonia water to generate NH4F. Activated carbon adsorbs residual SiF4 with an adsorption efficiency of 90%.

[0051] Open the drain valve of the drain pipe 23 at the bottom of the secondary absorption layer 9 to transport the solution to the ammonium fluoride drying unit. The single drain volume is approximately 1m³. 3 The flow controller 25 detects that its drain valve and flow controller 25 can be controlled by a PLC controller.

[0052] Phase 4: Deep purification and emission from the purification chamber 3

[0053] After secondary absorption, the exhaust gas enters the purification chamber's molecular sieve adsorption layer 3. The 16:13X type molecular sieve adsorbs fluoride ions through ion exchange, reducing the fluoride concentration in the outlet exhaust gas to 0.8 mg / m³. 3 ;

[0054] When the fluoride ion concentration detector shows an outlet concentration > 5 mg / m³ 3 At this time: stop the air intake, remove the mesh frame 21 and transfer the molecular sieve to the regeneration system, and reinstall it into the purification box 3 after regeneration.

[0055] Exhaust gas enters the baffle plate demister layer 17: the airflow turns and flows along the baffle plate, and the mist droplets hit the plate wall and drip down, with a mist droplet removal rate of 99%;

[0056] After purification, the exhaust gas is discharged from the top outlet 19 of the purification chamber 3. Online monitoring shows that the fluoride concentration is ≤1mg / m³. 3 It meets the GB31573-2015 ultra-low emission standard.

[0057] Phase 5: Equipment Maintenance

[0058] Weekly maintenance of the condenser box: Check the condenser tube wall through the cleaning port observation window. If the scale is ≥2mm, remove the sealing cover 27, and rinse with a high-pressure water gun or 5% dilute hydrochloric acid for 30 minutes after cleaning.

[0059] Monthly maintenance of absorption box 2: Remove the fluoroplastic corrugated packing layer 14 and replace the damaged packing; remove the activated carbon layer 15 and replace the saturated activated carbon; check the dilute sulfuric acid / ammonia water nozzle 13 and unclog any blocked nozzles.

[0060] Monthly maintenance of the purification chamber 3: Remove the molecular sieve adsorption layer 16 and regenerate or replace the molecular sieve; remove the baffle plate demisting layer 17 and rinse the plate wall to remove accumulated mist droplets.

[0061] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for recovering tail gas from hydrogen fluoride production, characterized in that, The system includes a condenser (1), an absorption chamber (2), and a purification chamber (3). The condenser (1) contains a staged condensation module, which includes a primary condenser (5) and a secondary condenser (6). A liquid collection tank is located at the bottom of the condenser (1). A partition plate is provided between the primary condenser (5) and the secondary condenser (6), with an opening on the partition plate. One end of the condenser (1) has an air inlet (4), and the other end is connected to the absorption chamber (2) via a pipe. The absorption chamber (2) is connected to the purification chamber (3) via a pipe. The absorption chamber (2) contains an absorption module. The purification box (3) is equipped with a purification module. The top of the purification box (3) is provided with an air outlet (19). The absorption module includes a fluoroplastic corrugated packing layer (14) and an activated carbon layer. The absorption box (2) is provided with a dilute sulfuric acid inlet (10) and an ammonia water inlet (11). The dilute sulfuric acid inlet (10) is adapted to the fluoroplastic corrugated packing layer (14), and the ammonia water inlet (11) is adapted to the activated carbon layer (15). The purification module includes a molecular sieve adsorption layer (16) and a baffle plate demister layer (17). The molecular sieve adsorption layer (16) is located below the baffle plate demister layer (17).

2. The hydrogen fluoride production tail gas recovery device according to claim 1, characterized in that, The absorption box (2) includes a primary absorption layer (8) and a secondary absorption layer (9). The primary absorption layer (8) and the secondary absorption layer (9) are connected. The fluoroplastic corrugated packing layer (14) is disposed in the primary absorption layer (8). The activated carbon layer is disposed in the secondary absorption layer (9). The dilute sulfuric acid inlet (10) is provided with a dilute sulfuric acid nozzle (12). The ammonia water inlet (11) is provided with an ammonia water nozzle (13). The dilute sulfuric acid nozzle (12) is perpendicular to the fluoroplastic corrugated packing layer (14). The ammonia water nozzle (13) is perpendicular to the activated carbon layer (15).

3. The hydrogen fluoride production tail gas recovery device according to claim 1, characterized in that, The condenser (1) has at least two cleaning ports on its side, and the cleaning ports are adapted to the primary condenser (5) and the secondary condenser (6). A sealing cover (27) is installed on the cleaning port by means of a bolt structure, and a transparent observation window (28) is provided on the sealing cover (27).

4. The hydrogen fluoride production tail gas recovery device according to claim 1, characterized in that, It also includes a mesh frame (21), the fluoroplastic corrugated filler layer (14), the activated carbon layer and the molecular sieve adsorption layer (16) are disposed in the mesh frame (21), the absorption box (2) and the purification box (3) are provided with filling ports, and the mesh frame (21) is slidably installed on the filling ports.

5. The hydrogen fluoride production tail gas recovery device according to claim 4, characterized in that, Below the demisting layer (17) of the baffle plate is a support frame (18), and the support frame (18) and the side of the mesh frame (21) are provided with a protective cover (20). The support frame (18) and the protective cover (20) are slidably installed on the filling port.

6. The hydrogen fluoride production tail gas recovery device according to claim 5, characterized in that, The loading port is provided with a bearing groove on both sides, and the bearing frame (18) and the protective cover (20) on the side of the mesh frame (21) are slidably connected to the bearing groove through the bearing rod (22).

7. The hydrogen fluoride production tail gas recovery device according to claim 2, characterized in that, At least two drain pipes (23) are provided below the condenser (1) and the absorption tank (2), and the drain pipes (23) are respectively connected to the liquid collection tank below the first-stage condenser (5), the second-stage condenser (6), the fluoroplastic corrugated packing layer (14) and the activated carbon layer. The drain pipes (23) are provided with drain valves (24), and the condenser (1) is provided with a liquid level sensor (26). The liquid level sensor (26) is located above the drain pipes (23), and the drain pipes (23) of the absorption tank (2) are provided with a flow controller (25).

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